You do not need the neutral for the air compressor or three phase loads. The
neutral is needed only for 120volt lighting and convenience outlets. Ground
conductors are needed for everything and must be kept seperate from the
neutral all the way back to the main service entrance panel.
Don Young
"Marty Escarcega" wrote in message
...
"Chief McGee" wrote in
news:eQTNc.204404$Oq2.30164@attbi_s52:

This was mentioned a few days ago but would someone please clarify it
for me.
I am installing 3-ph to the shop. It is 200A delta wound, 2
transformers on pole, 3 hot wires 1 neutral from pole, ground rod
driven into the dirt and hooked to the neutral buss bar. Drawing with
the meter box shows the neutral wire coming from the middle of one
side of the triangle that forms the delta. Is this what is called
"center tapped"?

Sounds like 120/208 to me...(though I'm 15 years rusty, I work on Traffic
Signals these days)

I think I want to run 5 wires to each machine. 3 hots, 1
neutral, and
one ground from the machine base all the way back to the neutral buss
bar in the sub panel. Is this right?

Nope. Run a 3 phase circuit for your machine, 3 hots and a ground. Fed
off the proper size 3 phase breaker.

Run a seperate circuit in a seperate conduit off say a 15 amp or 20 amp
single pole circuit breaker. Yes, some machines have a built in
transformer for a couple reasons, one to reduce the higher voltage to
single phase voltage for control contactors, single phase coolant pumps
and even lighting but you will find that there is a fuse usually on
either the primary or secondary side, sometimes both to protect the lower
current (amp) circuits. Put a light and related wiring on a 30amp 3 phase
breaker, and something goes wrong, the wiring will likely fry before a
breaker trips. That's why I suggest you run a dedicated circuit just for
your machine lighting.


I also want to have a 120 outlet and 120 work light on each
machine. AT
THE MACHINE, I am going to pick one of the hot legs(NOT the
power/stinger leg) and the neutral. Will connect the ground leg in
the light to the base of the machine. Is this right or do I have to
go all the way to the sub panel with the wires?

See the above, Also, I believe Jon Elson to be correct. the NEC requires
a seperate ground conductor. You can't rely on the conduit itself for a
ground. Why? Because they have found that electricians sometimes forget
to tighten the screws or lock nuts to keep the ground continuous, conduit
pulls apart, guess what, no safety ground.

Next, I have a 5-hp 220V single phase air compressor. For that
I
think I need only 4 wires. 2 hots(NOT the power leg) 1 neutral, and
one ground from chassis all the way back to the neutral buss bar in
the sub panel. Is this correct?

Yup for reasons states above, need a seperate ground now, you should be
running flexible metallic conduit to the compressor, you need the
seperate ground in that for the compressor, you could run heavy SO cord
too. As long as it was 4 conductor.


I want this to be safe and legal. Thanks for your time, Chief.

You have doubts, you should run the conduit, and call an electrician to
finish the job. Running the conduit is a good bit of work, let him pull
and terminate the wire. My disclaimer, my advice may or may not be
accurate, consult a licensed electrician for help....gawd I hate that....

Marty